Stemming dummy



Jam 5 w43- F. YAKES, JR 2,307,252

STEMMING DUMMY Filed Oct. 2l, 1940 INVENTQR Patented .lara 5, 1943 burg sk'rs gram' oFrlcE STEMMING DUMMY Frank Yakes, Jr., Lafayette, Colo.

Application October 21, 1940, Serial No'. 362,043

3 Claims.

This invention relates to a stemming dummy for blasting operations, more particularly for use in breaking down coal in coal mines, and is designated more particularly as an improvement over th'e stemming dummy illustrated in my prior Patent 2,254,405 patented September 2, 1941.

The principal object of the invention is to provide a device which will replace the usual sand and clay stemming now used for blocking drill holes after the explosive or expanding material has been placed therein.

Another object of the invention is to eliminate all screws, screw threads, and other rotating parts, such as illustrated in the said co-pending application, and to provide a mechanical stemming dummy which' can be operated much more rapidly than when threads are used and which will not be subjected to damage during the explosion.

Other objects and advantages reside in the f' detail construction of the invention, which is designed for simplicity, economy, and efficiency. These will become more apparent from the following description.

In the following detailed description of the invention reference is had to th'e accompanying drawing which forms a part hereof. Like numerals refer to like parts in all views of the drawing and throughout the description- In the drawing:

Fig. 1 is a side elevation of the improved stemming dummy,

Fig. 2 is a longitudinal section therethrough.

Fig. 3 is a section through a typical coal vein in a coal mine illustrating the invention in place therein.

In Fig. 3 a typical coal vein is illustrated at I0 having been under-cut, as shown at I I, and drilled with blasting holes I2. The explosive for breaking the coal is indicated in position in the blast hole at I3 with its attached fuse at I4.

Usually for such operations the entire drill hole I2 is packed with stemming which acts to confine the explosive action of the powder to the area immediately around the powder. This results in a breaking, shattering or powdering of the coal causing considerable loss. With the use of this invention, the entire hole, up to adjacent its outer extremity, is left for expansion of the exploding gases. Thus, a relatively long expanding area is provided which breaks down the coal from pressure more than from impact so as to reduce powdering and granulating of the coal.

The improved stemming dummy comprises a engage the latter and pull it to the right. rod will slide freely through the plates 26.

tubular body portion I5 provided at its inner 55 extremity with a gasket socket I6. A tension rod I1 extends through the body portion I5 and terminates in a head I8 within a head member I9. The head member is also provided with a gasket socket 20. A tip 22 is threaded into the extremity of the head member I9 and provides means for inserting and withdrawing the rod I1. The head member is formed with inclined gas passages 23 in its sides and the tip is also provided with a gas passage 24 extending axially therethrough.

A compressible, expansible, tubular gasket 2l is positioned about the rod I1 between the two gasket sockets I6 and 20. The gasket is preferably formed of heavy tread stock rubber but could be formed of any similar resilient, expansible material. It can be readily seen that if the rod I1 is withdrawn, through the member I5 it will act to compress the gasket 2| longitudinally causing it to expand transversely.

The withdrawing of the rod is accomplished by means of the following mechanism. A jack housing 25 is slipped over the protruding extremity of the-rod I1. The jack housing contains a plurality of locking plates 26 and pulling plates 21 actuated by compression springs 28 and 29, respectively. vThe rodv I1 passes through loosely fitting holes in all of the plates 26 and 21.

'Ihe plates 2B are formed with fulcrum arms 30 extending through a fulcrum opening 3| in the jack housing 25. The other extremities of the plates 26 are projected outwardly from the housing as illustrated.

The pulling plates 21 can be actuated by means of a forked lever 32, th'e fork of which engages the plates 21. The lever 32 is pivoted on a suitable pivot pin 33 in the housing 25 and is formed with a bar receiving socket 34 into which the extremity of a pry bar 35 may be inserted.

Let us assume that the pry bar 35 is swung in the direction of the arrow A, Fig. 2. Its forked extremity will pull the pulling plates 21 to the right. These plates will cock upon the rod I1 to The When the pry bar is released, the rod, in attempting to return under the inuence of the expansion of the gasket 2 I, will cock the plates 26, as shown in Fig. 2, to prevent the rod I1 from moving to the left. The pry bar 35 can now be swung to the right, the plates 21 striking an abutment 36 which releases them from the rod, and given another reciprocation to still further compress the gasket 2|.

To release the gasket, it is only necessary to hold the plates 26 by means of their projecting extremities at a right angular position so that they cannot cock and engage the rod Il.

The use of the device is believed to be readily apparent. It is simply inserted in the blasting holes I2, as shown in Fig. 3. The pry bar is reciprocated to cause the gasket to be expanded, as shown in this gure, to engage the walls of the drill hole to seal the latter and to lock the stemming dummy in place. After firing, the dummy is retrieved from the coal pile and reused.

For ring with fuses, the fuses are simply compressed into the gasket 2| which does not interfere with the ring. For use with expanding gases, such as carbon-dioxide, compressed air, etc., the rod Il is drilled throughout its entire length and a check valve 27 is installed in each extremity thereof. The rod l1 is connected to a compressed gas cartridge and the gas is forced through the rod into the drill hole to break down the coal.

While the invention has been described and illustrated with fuses, it is equally or more valuable when using electric firing wires.

If it is desired to use only one jack member for a plurality of dummies, a clamp collar 38 is placed about the rod I'l between the body portion I5 and the jack housing 25. The collar 38 has an open side which can be drawn together by means of a clamp bolt 39 to cause the collar to grip the rod and hold it in the withdrawn position. The jack device can then be removed and used to expand a second dummy. This also allows the jack device to be removed from the blasting zone so that it will not be damaged by the blast.

While a specific form of the improvement has been described and illustrated herein, it is desired to be understood that the same may be varied, within the scope of the appended claims, without departing from the spirit of the invention.

Having thus described the invention, what is claimed and desired secured by Letters Patent 1. A stemming dummy for insertion in blasting holes for sealing the latter against the force of the blast comprising: a tubular body portion; a tension rod extending through and projecting from both. extremities of said body portion; a head member on the inner extremity of said tension rod; a cylindrical compressible gasket about said rod between said head member and said body portion; a jack member mounted on the outer extremity of said housing; a lever hingedly mounted in said jack member; means for engaging said tension rod in consequence of the reciprocation of said lever to withdraw the latter through said body portion; and means independent of said jack positioned on said rod between the jack and the tubular body portion for locking said rod in the withdrawn position.

2. A stemming dummy for insertion in blasting holes for sealing the latter against the force of the blast comprising: a tubular body portion; a tension rod extending through and projecting from both extremities of said tubular body portion; a head member on one extremity of said tension rod; a cylindrical compressible gasket about said rod between said head member and said body portion; means for withdrawing said tension rod through said body portion to compress said gasket longitudinally for expanding it laterally; and means positioned between said body portion and said withdrawing means for holding said rod in the withdrawn position.

3. A stemming dummy for insertion in blasting holes for sealing the latter against the force of the blast comprising: a tubular body portion; a tension rod extending through and projecting from both extremities of said tubular body portion; a head member on one extremity of said tension rod; a cylindrical compressible gasket about said rod between said head member and said body portion; means for withdrawing said tension rod through said body portion to compress said gasket longitudinally for expanding it laterally; and a split collar surrounding said rod between said withdrawing means and said body portion for holding said rod in the withdrawn position.

FRANK YAKES, JR. 

